This patch adds new C APIs
dc_get_next_msgs() and dc_wait_next_msgs(),
and their JSON-RPC counterparts
get_next_msgs() and wait_next_msgs().
New configuration "last_msg_id"
tracks the last message ID processed by the bot.
get_next_msgs() returns message IDs above
the "last_msg_id".
wait_next_msgs() waits for new message notification
and calls get_next_msgs().
wait_next_msgs() can be used to build
a separate message processing loop
independent of the event loop.
Async Python API get_fresh_messages_in_arrival_order()
is deprecated in favor of get_next_messages().
Introduced Python APIs:
- Account.wait_next_incoming_message()
- Message.is_from_self()
- Message.is_from_device()
Introduced Rust APIs:
- Context.set_config_u32()
- Context.get_config_u32()
